Urethans isocyanates

Many important amines have been obtained by the hydrolysis of one of these substances. Thus, r-butylamine is formed by alkaline hydrolysis of f-butylurea (78%) or by treatment of r-butylisothiocyanate with formic acid (79%). Allylamine is synthesized by hydroiysis of ailyl isocyanate with dilute hydrochloric acid (73%). The hydroiysis of isocyanates, urethanes, and ureas, which occur as intermediates in the degradation of amides and azides, has been discussed under methods 446 and 447, where many examples have been cited. 

Thioanalogs of ketones, acetals, carboxylic acids, esters, amides, ° isocyanates, " urethanes, and ureas are often prepared by reactions similar to those used for... 

The preparation of acyl azides has received considerable attention due to the value of these compounds as synthetic intermediates. In the Gurtius rearrangement for example, acyl azides arc converted into isocyanates, urethans, ureas and amines and this aspect of the chemistry of acyl azides is considered in detail in a later chapter. The use of acyl azides in peptide synthesis has increased the scope of general... 

Covers one type of inert-gas-expanded isocyanate urethane foam, closed-cell, for use in rocket motors. 

Saunders and Frisch (2) cite certain catalysts used to Induce an isocyanate-urethane (allophanate) reaction. They are zinc octoate, cobalt napthanate and cobalt octoate and are claimed to yield 95% allophanate. An experiment was designed observing the catalytic effect of these metal complexes under varied concentrations and over time. Ferric acetylacetonate, a catalyst known to Influence an isocyanate-carboxyl reaction, was included 1n the study. The catalysts were added individually and 1n combinations of two into a polyurethane-polyisocyanate system. Concentrations varied from 1.50% to 8.00% by weight. 

Although this reaction is reversible it could be driven to the right if the dissociated fragments undergo subsequent side reactions or in some way become less available to one another for recombination. Morphology could play a role since the polymer prepared from PPG 1000 is stable at 204°C. even though it has twice the number of polyol to isocyanate urethane bonds available for dissociation. 

Carbonyl azides are usually obtained from the hydrazides, although in principle they can also be prepared directly from the carbonyl chlorides and sodium azide. They are frequently used as intermediates for synthesis of isocyanates, urethanes, ureas, amines, etc., and are often used in such work without isolation. 

Acylation —esters Trimethylsilation—silyl esters Isocyanates—urethanes... 

A biobased non-isocyanate urethane could be obtained by the reaction of a cyclic carbonate synthesized from a modified linseed oil and an alkylated phenolic polyamine from cashew nut shell liquid (18). The incorporation of the functional cyclic carbonate moieties to the triglyceride units of the oil was done by reacting epoxidized linseed oil with carbon dioxide in the presence of a catalyst. The reaction is shown schematically in Figure 6.7. 

Related articles include Wood adhesives - hot melts, Wood adhesives - isocyanates/ urethanes, Wood adhesives - phenolics and Wood composites - adhesives. 

Wood adhesives - isocyanates/urethanes A PIZZI Bonding to damp wood... 

Isocyanate-urethane and isocyanate-urea reactions then yield biurets and allophanates, which produce crosslinking and branching ... 

Azides can be rearranged in inert solvents like benzene and chloroform, from which the isocyanates can be isolated, or in the presence of reagents like alcohol or water which will react with the intermediate isocyanates to form urethans or ureas. Amines or their salts are obtained by hydrolysis of the isocyanates, urethans, or ureas. 

Starting Material Hydrazide Azide Isocyanate Urethan Amine, etc. 

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